High rate of indeterminate results of the QuantiFERON-TB Gold in-tube test, third generation, in patients with systemic vasculitis

Abstract

Objectives To describe the frequency of QuantiFERON-TB Gold in-tube test® (QFT-GIT) indeterminate results due to no response to phytohaemagglutinin A stimulation in the control tube in vasculitis patients prior to immunosuppressant therapy; and to compare it with other groups of patients. Methods This was a single-centre, retrospective study. Patients and controls were included between 1 January 2008 and 31 December 2015. We assessed the rate of indeterminate results of the QFT-GIT in 38 patients with systemic vasculitis prior to any corticosteroid or immunosuppressant therapy, compared with 40 non-vasculitis patients with biological inflammatory syndrome, and 310 non-immunosuppressed patients matched for gender and age. Results Indeterminate results due to no response to phytohaemagglutinin A were more frequent in vasculitis patients (21.1%) compared with non-vasculitis patients with biological inflammatory syndrome (7.5%) (Fisher's exact test: P = 0.11) and to anonymized controls (7%) (P = 0.009). Responses to phytohaemagglutinin A were significantly lower in vasculitis patients compared with other groups (Kruskal–Wallis test: P < 0.0001) and compared with non-vasculitis patients with biological inflammatory syndrome (P = 0.0015). The multivariable analysis identified as independent predictors of an indeterminate result of the QFT-GIT: the presence of systemic vasculitis (odds ratio 9.64 [1.14–81.3], P = 0.037) and a high neutrophil-to-lymphocyte ratio (odds ratio 1.70 [1.21–2.37], P = 0.002). One patient with an indeterminate result of QFT-GIT developed active tuberculosis after one year of corticosteroid therapy for giant cell arteritis. Conclusion Our results question the reliability of QFT-GIT to rule out latent tuberculosis in vasculitis patients at diagnosis, prior to immunosuppressant therapy.

Performance of LTBI Screening in Patients with Rheumatic Diseases Using Two Different Interferon-Gamma Releasing Assays

“…Furthermore, our study discovered that low lymphocyte count was associated with QFT-GIT indeterminate results. However, high SLEDAI scores seemed not related with a high proportion of indeterminate results, and this differs from some studies [20][21][22][23][24]. Other previous researches showed that CD4+ T cell count, lymphocyte count, and lymphocyte percentage were influencing factors for the indeterminate results of QFT-GIT in HIV and immunosuppressive people [25,26].…”

Interferon-gamma Release Assay Results Are Reliable for Screening for Latent Tuberculosis in Antineutrophil Cytoplasmic Antibody-associated Vasculitis

“…Based on these results, two hypotheses are proposed: first, the pattern of the inverse correlation is thought to be due to IFN-gamma producing T cell exhaustion, as shown in our previous study on systemic lupus erythematosus (SLE) (12). Several studies have supported this phenomenon by showing a marked decrease in T-cell responses to phytohemagglutinin A in patients with autoimmune diseases (18,19). Second, the absence of statistical significance of this pattern indirectly indicated that the proportion of IFN-gamma in the pathogenesis of AAV is relatively smaller than that in SLE (8,20).…”

Glucocorticoid use as a cause of non-cellular immune response to SARS-Cov2 Spike in patients with immune system diseases

“…Several parameters were previously demonstrated to influence the T cell response in the IGRA assay [ [13] , [14] , [15] ]. They included PMN and lymphocyte counts, a defective T cell capacity to respond to PHA stimulation (IGRA-PHA), GC dose, and serum albumin level.…”